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The crystal-structure determination and redefinition of eztlite, Pb2+2 Fe3+3(Te4+O3)3(SO4)O2Cl


Missen, OP and Mills, SJ and Spratt, J and Welch, MD and Birtch, W and Rumsey, MS and Vylita, J, The crystal-structure determination and redefinition of eztlite, Pb2+2 Fe3+3(Te4+O3)3(SO4)O2Cl, Mineralogical Magazine, 82, (6) pp. 1355-1367. ISSN 1471-8022 (2018) [Refereed Article]

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DOI: doi:10.1180/mgm.2018.108


The crystal structure of eztlite has been determined using single-crystal synchrotron X-ray diffraction and supported using electron microprobe analysis and powder diffraction. Eztlite, a secondary tellurium mineral from the Moctezuma mine, Mexico, is monoclinic, space group Cm, with a = 11.466(2) , b = 19.775(4) , c = 10.497(2) , β = 102.62(3) and V = 2322.6(9) 3. The chemical formula of eztlite has been revised to forumla|${\rm Pb}_{\rm 2}^{2 +} {\rm Fe}_3^{3 +} $|(Te4+O3)3(SO4)O2Cl from that stated previously as forumla|${\rm Fe}_6^{3 +} {\rm Pb}_{\rm 2}^{2 +} $|(Te4+O3)3(Te6+O6)(OH)10nH2O. This change has been accepted by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, Proposal 18-A. Eztlite was reported originally to be a mixed-valence Te oxysalt; however the crystal structure, bond-valence analysis and charge balance considerations clearly show that all Te is tetravalent. Eztlite contains a unique combination of elements and is only the second Te oxysalt to contain both sulfate and chloride. The crystal structure of eztlite contains mitridatite-like layers, with a repeating triangular nonameric [forumla|${\rm Fe}_9^{3 +} $|O36]45 arrangement formed by nine edge-sharing Fe3+O6 octahedra, decorated by four trigonal pyramidal Te4+O3 groups, compared to PO4 or AsO4 tetrahedra in mitridatite-type minerals. In eztlite, all four tellurite groups associated with one nonamer are orientated with the lone pair of the Te atoms pointing in the same direction, whereas in mitridatite the central tetrahedron is orientated in the opposite direction to the others. In mitridatite-type structures, interlayer connections are formed exclusively via Ca2+ and water molecules, whereas the eztlite interlayer contains Pb2+, sulfate tetrahedra and Cl. Interlayer connectivity in eztlite is achieved primarily by connections via the long bonds of Pbφ8 and Pbφ9 groups to sulfate tetrahedra and to Cl. Secondary connectivity is via TeO and TeCl bonds.

Item Details

Item Type:Refereed Article
Keywords:eztlite, crystal structure, tellurite, synchrotron radiation, tellurium oxysalt, mitridatite
Research Division:Earth Sciences
Research Group:Geology
Research Field:Mineralogy and crystallography
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Other mineral resources (excl. energy resources)
Objective Field:Other mineral resources (excl. energy resources) not elsewhere classified
UTAS Author:Missen, OP (Dr Owen Missen)
ID Code:154949
Year Published:2018
Web of Science® Times Cited:3
Deposited By:CODES ARC
Deposited On:2023-01-20
Last Modified:2023-01-25

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